IMHO the only aircraft available at that time that was in the ballpark for competing with the Jaguar in the light strike role in terms of avionics, range and warload was the A-7. I prefer the Jag as it was much quicker (mach 1.6 vs mach .9) and had two engines for sustained over water operations, plus it was specifically designed to work in the STOL role in austere environments. The last two points were potentially very important in Australia's AO.
Another non-Jag opton alternative might have been to keep the F-4E's and buy extra's once the F-111 came into service, but use them to replace the Mirage's in the air to air role. Then we could upgrade the Mirage's a la Kfir with J-79's, canard forplanes and perhaps a strike radar like Agave and transfer them to the light strike role. That would give us some commonalities with engines, a longer range and more capable air to air fighter while saving money by using the Mirage airframes in the air to ground role. The F-4's could then be replaced by F-15's and the Mirages by F-16's or F-18's from the mid-80's.
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